Auto merge of rust-lang#137918 - matthiaskrgr:rollup-7rozmxw, r=matthiaskrgr

Rollup of 10 pull requests

Successful merges:

 - rust-lang#132388 (Implement `#[cfg]` in `where` clauses)
 - rust-lang#134900 (Fix parsing of ranges after unary operators)
 - rust-lang#136938 (Remove `:` from `stack-protector-heuristics-effect.rs` Filecheck Pattern)
 - rust-lang#137054 (Make phantom variance markers transparent)
 - rust-lang#137525 (Simplify parallelization in test-float-parse)
 - rust-lang#137618 (Skip `tidy` in pre-push hook if the user is deleting a remote branch)
 - rust-lang#137685 (self-contained linker: conservatively default to `-znostart-stop-gc`)
 - rust-lang#137741 (Stop using `hash_raw_entry` in `CodegenCx::const_str`)
 - rust-lang#137849 (Revert "Remove Win SDK 10.0.26100.0 from CI")
 - rust-lang#137862 (ensure we always print all --print options in help)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -3438,6 +3438,32 @@ fn add_lld_args(
     // this, `wasm-component-ld`, which is overridden if this option is passed.
     if !sess.target.is_like_wasm {
         cmd.cc_arg("-fuse-ld=lld");
+
+        // GNU ld and LLD have opposite defaults on some section garbage-collection features. For
+        // example, the somewhat popular `linkme` crate and its dependents rely in practice on this
+        // difference: when using lld, they need `-z nostart-stop-gc` to prevent encapsulation
+        // symbols and sections from being garbage-collected.
+        //
+        // More information about all this can be found in:
+        // - https://maskray.me/blog/2021-01-31-metadata-sections-comdat-and-shf-link-order
+        // - https://lld.llvm.org/ELF/start-stop-gc
+        //
+        // So when using lld, we restore, for now, the traditional behavior to help migration, but
+        // will remove it in the future.
+        // Since this only disables an optimization, it shouldn't create issues, but is in theory
+        // slightly suboptimal. However, it:
+        // - doesn't have any visible impact on our benchmarks
+        // - reduces the need to disable lld for the crates that depend on this
+        //
+        // Note that lld can detect some cases where this difference is relied on, and emits a
+        // dedicated error to add this link arg. We could make use of this error to emit an FCW. As
+        // of writing this, we don't do it, because lld is already enabled by default on nightly
+        // without this mitigation: no working project would see the FCW, so we do this to help
+        // stabilization.
+        //
+        // FIXME: emit an FCW if linking fails due its absence, and then remove this link-arg in the
+        // future.
+        cmd.link_arg("-znostart-stop-gc");
     }
 
     if !flavor.is_gnu() {

compiler/rustc_expand/src/base.rs

@@ -53,6 +53,7 @@ pub enum Annotatable {
     Param(ast::Param),
     FieldDef(ast::FieldDef),
     Variant(ast::Variant),
+    WherePredicate(ast::WherePredicate),
     Crate(ast::Crate),
 }
 
@@ -71,6 +72,7 @@ impl Annotatable {
             Annotatable::Param(p) => p.span,
             Annotatable::FieldDef(sf) => sf.span,
             Annotatable::Variant(v) => v.span,
+            Annotatable::WherePredicate(wp) => wp.span,
             Annotatable::Crate(c) => c.spans.inner_span,
         }
     }
@@ -89,6 +91,7 @@ impl Annotatable {
             Annotatable::Param(p) => p.visit_attrs(f),
             Annotatable::FieldDef(sf) => sf.visit_attrs(f),
             Annotatable::Variant(v) => v.visit_attrs(f),
+            Annotatable::WherePredicate(wp) => wp.visit_attrs(f),
             Annotatable::Crate(c) => c.visit_attrs(f),
         }
     }
@@ -107,6 +110,7 @@ impl Annotatable {
             Annotatable::Param(p) => visitor.visit_param(p),
             Annotatable::FieldDef(sf) => visitor.visit_field_def(sf),
             Annotatable::Variant(v) => visitor.visit_variant(v),
+            Annotatable::WherePredicate(wp) => visitor.visit_where_predicate(wp),
             Annotatable::Crate(c) => visitor.visit_crate(c),
         }
     }
@@ -128,6 +132,7 @@ impl Annotatable {
             | Annotatable::Param(..)
             | Annotatable::FieldDef(..)
             | Annotatable::Variant(..)
+            | Annotatable::WherePredicate(..)
             | Annotatable::Crate(..) => panic!("unexpected annotatable"),
         }
     }
@@ -223,6 +228,13 @@ impl Annotatable {
         }
     }
 
+    pub fn expect_where_predicate(self) -> ast::WherePredicate {
+        match self {
+            Annotatable::WherePredicate(wp) => wp,
+            _ => panic!("expected where predicate"),
+        }
+    }
+
     pub fn expect_crate(self) -> ast::Crate {
         match self {
             Annotatable::Crate(krate) => krate,
@@ -446,6 +458,10 @@ pub trait MacResult {
         None
     }
 
+    fn make_where_predicates(self: Box<Self>) -> Option<SmallVec<[ast::WherePredicate; 1]>> {
+        None
+    }
+
     fn make_crate(self: Box<Self>) -> Option<ast::Crate> {
         // Fn-like macros cannot produce a crate.
         unreachable!()